1. Field of the Invention
The present invention relates to a monitor (surveillance) camera system covering 360-degree monitoring area and an auto-tracing method of automatically tracing (passing) monitoring points successively through the use of a monitor camera, and more particularly to a monitor camera system and an auto-tracing method which are capable of implementing the auto-tracing accurately.
2. Description of the Related Art
So far, a monitor camera in which a camera and a rotatable table therefor are placed in a dome-like housing has been put on the market. This monitor camera is called a “compound camera” because of the camera being capable of, through movements of the rotatable table, rotating horizontally (pan) while rotating vertically (tilt). It can rotate through 360 degrees without limitation in the pan directions, while rotating in an angular range between 0 degree and 90 degrees, that is, from a horizontal direction to a vertical direction, in the tilt directions. In addition, through the manipulation of a controller, this compound camera can take a photograph at a desired angle or in a desired direction in a state installed on a ceiling of public facilities or the like. Still additionally, even if a target subject passes right under it, as FIG. 10 shows, immediately a camera 10 turns to right under, it can rotate 180 degrees around a lens thereof to chase the target subject continuously, thus providing pictures throughout a monitoring area.
FIG. 8 is an illustration of a state in which a controller 12 for controlling a compound camera 11 and a monitor 13 for displaying a picture taken through the compound camera 11 are connected through a coaxial cable 16 to the compound camera 11. The controller 12 functions as a control element and comprises a joystick 14 and a numeric pad (numeric keys) 15.
This compound camera 11 is designed so that a plurality of camera positions, for example, taking a direction to an entrance, a direction to an exit and a direction to a window, are preset in the controller 12 in the form of identification numbers (ID). After preset, simply by inputting the ID corresponding to a camera position through the use of the numeric pad 15, the camera can be turned to take the preset direction.
In addition, the joystick 14 of the controller 12 is manipulated for controlling the moving (rotating) speed of the camera 11. When the joystick 14 is tilted, as shown in FIG. 9, the camera 11 rotates in a tilting direction at a speed proportional to the movement component of the joystick 14 in the vertical-axis direction and rotates in a panning direction at a speed proportional to the movement component thereof in the horizontal-axis direction. An operator checks pictures while viewing the monitor 13 and, when the rotating camera 11 catches a desired direction, the operator returns the joystick 14 to the neutral position to stop the rotation thereof in the tilting and panning directions.
In addition, this monitor camera system can perform auto-tracing by making the controller 12 store a plurality of monitoring spots to be monitored by the camera 11 to display the pictures of the plurality of monitoring spots in rotation in accordance with an instruction from the controller 12.
However, according to the conventional monitor camera system, since the instruction on the monitoring spots for the auto-tracing is issued from the controller 12, a delay in arrival of instruction data at the monitor camera 11 occurs owing to transmission delay or the like, which creates a problem in that difficulty is experienced in accomplish the auto-tracing accurately as set initially.